Crankshaft chuck



May 6, 1941. w. 1.. GROENE CRANKSHAFT CHUCK Filed Dec. 22, 19:59

2 Sheets-Sheet 1 Patented May 6, 1941 UNITED STATES PATENT OFFICECRANKSHAFT CHUCK Willard L. Groene, Cincinnati, Ohio, assignor to l TheR. K. Le Blond Machine Tool Company,

Cincinnati, Ohio, a corporation of Delaware Application December 22,1939, Serial No. 310,589

16 Claims. (Cl. 82-40) This invention pertains to chucking mechanism foruse in connection with gripping prelocated, rough irregular work piecesin a lathe. More particularly this invention pertains to the chucking ofcrankshafts, having rough, irregular webs and prelocated in a lathe forpurposes of machining bearing portions of the crankshaft. Specifically,this invention is applicable to the center drive type of lathe formachining'all of the line bearings, flange, and stub ends ofcrankshafts, for example, as shown in Patent 2,069,107, dated January26, 1937.

Heretofore all chucking devices used for accomplishing the accuratechucking of a prelocated work piece having rough irregular surfaces,such as the rough irregular webs of a crankshaft, have all beenimpractical and lacking in accurate results. The chief defects whichhave been characteristic and inherent in such former chucking deviceshave been:

(a) To utilize the prelocated work piece to initially locate andposition the work engaging portion of the chucking'device during initialengagement of the chucking device with the work piece,

(b) Utilization of clamping action which brought the chuck device intoengagement with the Work piece in a direction perpendicular to the axisof rotation of the Work piece in. the lathe.

In the first instance difiiculty rises since the I work piece must beextremely rigid to withstand the strain imposed upon it during theinitial engagement of the chucking device therewith and during the timethis chucking member is being bound on to the work piece. This method ofgripping the rough irregular work piece, such as a crankshaft, is foundwholly impractical because the crankshaft is of such a limber naturethat any such engagement of a chucking member on the web of thecrankshaft during the initial clamping invariably distorts thecrankshaft from its true accurate position on the axis of the lathe. Itis to be remembered that the objective in a lathe of this kind is tochuck the crankshaft so accurately that the runout will be onethousandth of an inch or less in order that subsequent finish grindingmaybe undertaken directly upon the bearings which have been turned insuch a lathe, and so that the runout of these bearings will be soaccurate as to prevent any possibility of lack of finishing up thesebearings during these finish grinding operations. Runout, as commonlyused in the turning art, means the relative eccentricity of the bearingsfrom their true axis of rotation. Such type chucks which operate withthe defective principle above may be classified as chucks of a typewhich have a work engaging member which is first clamped up on the workpiece and then this work engaging member is later locked frictionally tothe work spindle of the lathe upon which it is mounted, such chucks forexample being of a type shown in Patent 1,617,403, dated February 15,1927.

The second type of chucking device which is automatically compensating,but which has clamping action in a direction perpendicular to theaxis ofrotation of the work piece in the lathe, is defective because suchdirection of clamping action during the final tightening stages tends toa move the crankshaft from true prelocated position on the axis of thelathe so that the crankshaft will be chucked inaccurately and after thecompletion of the machining operation will spring back to cause thecrankshaft to have excessive runout of the bearing portions machinedwhen again unchucked after the turning opera: tion. Such type chucks,for example, may be i1- lustrated by Patent 2,160,967, dated June 6,1939, in which the work engaging members are finally engaged on the workpiece by radial movement toward the axis of rotation of the work pieceto be machined.

It is therefore, the primary object of this invention to completelyavoid either of these principles of a former rough work engagingchucking devices and to completely depart from the old ideas usedtherein and to provide a chucking device which is fully equalizinglongitudinally or lengthwise of the axis of rotation of the work to beturned but which has no relative movement on the work spindle in anyradial or circumferential direction in a plane perpendicular to saidaxis of rotation.

Another important and distinct feature of this new invention is toprovide a chucking device for engaging a rough irregular prelocated workpiece in a lathe which engages the work in such a way that the clampingaction of the chucking device on the work pieces takes place in a linesubstan- Q tially parallel with the axisof-rotation of the Work piece inthe 'lathe so that no matter how tightly said clamping device is bound.upon the work piece it can have no efiect whatever on the axial orradial displacement of the work piece from its true prelocated positionon the work spindle axis of the lathe.

A further object is to provide a chucking de vice which is adapted toengage a rough irregular work piece without distorting or bending itfrom its true axial position by effecting clamping,

action in a direction parallel with the axis of rotation of the workpiece in the chuck while at the same time allowing free axial floatingof the work piece longitudinally of said axis for endwise position ofthe crankshaft by means independent of the chucking device.

And a still further feature of this invention is to provide in a centerdrive lathe. a pair of chucking devices each adapted to engage a rough,prelocated work piece by means movable in a direction substantiallyparallel to the axis of rotation of the lathe, one of said chuckingdevices chucking device relative to said axis of rotation.

Further features and advantages of this in vention will appear in thefollowing detailed d scription of the drawings in which:

Fig. I is an axial View of a pair of center drivev on the line IIIIII ofFig. 11. 1

For illustrative purposes this invention is shown applied to the ringgears l and 2 of a double center drive line bearing crankshaft lathe ofa type, for example, as' illustrated in Patent 2,069,107 cited above, inwhich a crankshaft C, having line bearings 3, 4 and 5, the stub end 6and flange end I, the pin bearings 8, 9, H3, ll, and interconnectingwebs l2, I3, 14, l5, l5 and I? is mounted on the usual lathe centers l8and 19. In this type of lathe the cutting tools (not shown) are adaptedto machine the'line bearings 3, i, 5 and the stub end 8 and flange end 1of the crankshaft in a single operation. Having thus placed the workcrankshaft C on the centers i8 and [9, its axis of rotation 2il -willthen properly coincide with the axis of rotation of the ring gears I and2 of the lathe. The problem then is to properly grip this crankshaftintermediate these centers land I9 so as to very rigidly and positivelyhold the crankshaft against any distortionwhich mayv come upon it duringthe application of the cutting tools to thevari ous line bearingportions-but which also is capable of gripping the shaft initially withthis rigid positive action without in any way moving the crankshaft or,bending it out of proper axial alignment with the axis of rotation 20-of the lathe. In order to do this the object of this invention istoavoid .the usual application of a gripping member to the roughperiphery of the webs of the crankshaft and then locking this grippingmember to the ring gears or to apply any chucking membersto theperiphery of these webs of the shaftwith clamping force exerted inaplane perpendicular to this axis 20. Rather it is the object of thisinvention to applygripping jaws 2i and 22 which engage the sides 21a and22a of the respective webs l3 and of the crankshaft in a directionparallel with the axis of rotation 29 of the lathe.-

In this particularillustration a pair of center drive ring gears iand 2areshown'but insofar as the detail constructions of the chuckingmechanism in each of the ringgears is concerned they being locateddiametrically opposite the other are substantially the same in both ringgears so that the discussion of the mechanism in one of said ring gearswill suffice for that of the other ring gear.

Noting particularly Fig. II, each of the work engaging jaws 2| and 22are pivotally mounted on a hinge pin 23 which is securely fixed in thesegmental member 24, fixed into the ring gears l and 2 by appropriatescrews 25. This pivotal hinge mounting of these jaws 2| and 22 is soarranged that the serrated end portions 2m and 2211 move substantiallyparallel to the axis of thelathe to engage the rough Web surfaces 13aand lfia of the crankshaft C.

I In order .to prevent movement of these gripping jaws 2i and 22 otherthan axial swinging movement parallel with the axis 2!] of thecrankshaft, the edges 26 of each of the jaws nicely fit between thesides 21 of the slots 28 formed in the segmental piece 24 so .that theycan have no relativeLmovement with respectto the chuck body in a plane,perpendicular to the axis 20 of the .chuclnthe hinge pin 23 preventingall radial movement of saidjaws withrespect to the ring s rs.

It1is thus apparent that with this unique arrangement: thoroughness. orirregularities of the webs. l3 andglfi can have no effect on .theposition of the'jaws 2! and 22 in a plane perpendicular to the axis 29of the lathe, so that the difiloulties in former devices of attemptingto accurately radially position the work engaging jaws in thisperpendicular plane by engagement with the. rough web surface iscompletely avoided. The positioning of these jawsilongitudinally oftheaxisZO is of no consequence and in no way effects. the radiallypositioning of the crankshaft inproperalignment with. the axis 20. Thesejaws are purposely made floating in this respect to prevent binding ofthe crankshaft axially between the ring gears I and, Brand to permit theI centers i8and l9 to be properly adjusted for axiallyi or endwisepositioning of the crankshaft in the lathe relative to the cuttingtools.

In order to securely bind these jaws 2| and 22 upon, the webs I3 and [6of the crankshaft, the clamping screw- 29 is provided having a suitablewrench socket 253a provided in its head and which may be, operated bymeans of a hand wrench or by means of a power chucking device of thetype shown in. pplication, Serial No. 298,230 dated October 6, 1939.This clamping screw;29 is suitable threaded-at 33 in one of the jaws so,that as the screwis properly rotated these jaws: may; bepostivelybrought together to literally pinch the web l3 or it betweenthe serrated ends Zia; and 22a of the respective chuck jaws;Arelatively-light compression spring 3! is-provided aroundthe screw 29and'between-the two; gripping jawsfll and 22 to normally urge themoutwardly, disengaging their serrated portions'from the webwhen theclamping screw 29 is loosened; so that these'webs will be properlyfreedfrom contact with clamping jaws for loading or unloading thecrankshaft into the lathe.

The operation of such a double center drive with thisnovel arrangementis substantially as follows:

flihe crankshaft is first entered axially in to the center drive ringgears by means of a load:

ithasbeen properlyaxially positioned along the axis 20-tin theringgears. The loading device is then operated to lowerthe crankshaftradially of the axis 20, bringing the webs l3 and I6 downwardly betweenthe respective chuck jaws 2| and 22 of each ring gear. The centers I8and 19 are then moved inwardly to engage and pick up the crankshaft sothat the loading crane device may then be removed from the lathe in amanner fully described in the cited Patent 1,700,721. Having thusprelocated the workshaft C in the lathe on the axis 28, the clampingscrews 29 are then appropriately tightened to bind thejaws 2| and 22 onthese webs l3 and N of the crankshaft C. The crankshaft is now properlygripped ready for the completion of the cutting operations in thisinstance, on all of the line bearing portions, the stub, and flange endsof the crankshaft. 'At the completion of these turning operations theclamping screws 29 are released, the springs 3| removing the jaws fromengagement with the web l3 and I6 and the loading device then is movedinwardly to engage the work crankshaft C. Centers I8 and I9 are thenwithdrawn and the work raised radially upwardly and then moved axiallyoutwardly through the space 32 in the ring gears completing theunloading and the machining cycle of the lathe.

Having thus fully set forth and described my invention what I claim is:

1. In a lathe, a pair of centers adapted to engage and'prelocate a workpiece on the axis of rotation of said lathe, a rotatable work spindle,work engaging members on said work spindle arranged to engage saidprelocated work piece in a direction substantially parallel to said axisof rotation of said lathe, and means preventing movement of said membersperpendicular to said axis of rotation.

2. In a lathe, a pair of centers adapted to engage and prelocate a workpiece on the axis of rotation of said lathe, a center drive ring gearintermediate said centers, chucking mechanism in said ring gear adaptedto engage by engagement said work piece in a direction substantiallyparallel to said axis of rotation, and means preventing movement of saidmembers perpendicular to said axis of rotation.

3. In a lathe, a pair of centers, a pair of center drive ring gearsintermediate said centers, work engaging chucking mechanism in each ofsaid ring gears, means for effecting clamping of said chucking mechanismon a work piece prelocated on said centers by movement of said workengaging members in a direction substantially parallel to said axis ofrotation of said lathe, and means preventing movement of said membersperpendicular to said axis of rotation.

4. In a lathe, a pair of centers, a pair of center drive ring gearsintermediate said centers, work engaging members in each of said ringgears, the work engaging members of said ring gears being located ondiametrically opposite sides of said axis of rotation, means foractuating said members to engage said work piece in a directionsubstantially parallel to the axis of rotation of said lathe, and meanspreventing movement of said members perpendicular to said'axis ofrotation.

5. In a lathe, a pair of centers, 2. center drive ring gear between saidcenters, chucking mechanism in said ring gear comprising a pair ofopposed rough work engaging jaws mounted in said ring gears for movementsubstantially parallel to the axis of rotation of said lathe, means foreffecting clamping of said pair of work engaging members on a roughprelocated work piece on the centers of said lathe and means preventingradial movement of said jaws relative to said axis of rotation. I

6. In a lathe, a pair of centers adapted to prelocate awork piece on theaxis of rotation of said lathe, a pair of center drive ring gearsintermediate said centers, chucking mechanism in each of said ring gearseach comprising a pair of work engaging members and means for movingsaid work engaging members in a direction substantially parallel to theaxis of rotation of said lathe to clamp said work engaging members onsaid rough prelocated work piece on the axis of rotation of said lathe,and means preventing movement of said members radially of said axis.

7. In a lathe, a rotatable work spindle, a pair of work engaging jawspivotally mounted on said work spindle having serrated work engagingsurfaces for engaging a rough prelocated work piece in a lathe, aclamping screw passing through one of. said jaws and threaded into theother of said jaws, resilient means for urging said jaws away from eachother, and means for rotating said screw to eifect clamping action ofsaid jaws on said work piece in a direction'substantially parallel tothe axis of rotation of said lathe.

8,.In a lathe, a rotatable work spindle, a pair of work engaging jawspivotally mounted on said work spindleagainst any radial orcircumferential movement on said work spindle, means for drawing saidjaws together to effect clamping of said jaws on a work piece in saidlathe in adirection substantially parallel to the axis of rotation ofsaid lathe, and means permitting axial float of said work piece and saidclamping devices relative to said work spindle.

9. In a lathe, a pair of centers for engaging the ends of a Work pieceto prelocate it on the proper axis of rotation in said lathe and toaxially position said work piece longitudinally of said axis, a rotarywork spindle mounted in said lathe, chucking mechanism on said spindlehaving work engaging members adapted to engage said work piece bymovement in a direction substantially parallel to the axis of rotationof said lathe, and means on said spindle to prevent movement of saidmembers perpendicular to said direction of engaging movement.

10. In a crankshaft lathe, a pair of centers adapted to engage the endsof a crankshaft to be machined to position said crankshaft on the axisof rotation of said lathe, a center drive ring gear rotatably mounted insaid lathe, rough work engaging members in said chuck adapted to engagethe sides of a web of said crank shaft, means for binding said clampingmechanism to the sides of said web by movement of said gripping membersin a direction substantially parallel to the axis of rotation of saidwork piece in the lathe, and means to prevent movement of said membersin any other direction.

11. In a double center drive crankshaft lathe, a pair of centers adaptedto engage the ends of a rough crankshaft to be machined in said lathe, apair of rotatable ring gears journaled in said frame, chucking mechanismin each of said ring gears comprising members adapted to engage thesides of webs of said crankshaft, means for effecting clamping of saidmembers to said webs by movement in a direction substantially parallelto the axis of rotation of said lathe, and means in said ring gearpreventing radial movement of said members relative to said axis.

12. In a double center drive crankshaft lathe, a pair of centers, a pairof center drive ring gears mounted in said lathe intermediate saidcenters,

chucking mechanism in each of said ring gears comprising a pair ofclamping jaws adapted .to engage the sides of webs of said crankshaft,clamping means associated with said clamping jaws to bind said jaws tosaid Web by movement of said jaws in a direction substantially parallelto the axis of rotation of said lathe, and means in said. ring gearspreventing radial movement of said jaws relative to said axis.

13. In a double center drive crankshaft lathe, a pair of centers adaptedto prelocate a crankshaft on the proper axisof rotation in said lathe, apair of double center drive ring gears, chucking mechanism in each ofsaid ring gears each .comprising members adapted to .engage the sides ofwebs 'of said crankshaft, means for clampingsaid jaws to said webs bymovement substantially parallel to the axis of rotation of said lathe,said chucking mechanism in one of said chucking devices being locatedsubstantially diametrically opposite the chucking mechanism in the otherof said ring gears with respect to saidaxis of rotation of said ringgears, and means in said ring gears preventing radial movement of saidjaws relative to said axis.

1 4. In a double center drive crankshaft lathe, a pair of centers,adapted to engage the ends of a rough crankshaft to be machined and toprelocate said crankshaft on the proper axis of rotation of said latheand to axially position said crankshaft longitudinally of said axis, apair of rotatable center drive ring gears in said lathe, chuckingmechanism comprising work engaging membersin each of said ring gearsfioatingly mounted for movement substantially parallel to the axis ofrotation of said lathe, means for effecting clamping of .said workengaging'members of said chucking mechanism on the sides of webs. ofsaid crankshaft, said means effecting movement in said memberssubstantially parallel to the axis of rotation of said lathe, and meansin each of said ring gears preventing any movementofsaid members in aplane perpendicular tosaid axis ofrotation of said ring gears of saidlathe.

15. In a chucking device for lathes, a rotatable work spindle, a pair ofchucking jaws mounted for axial floating movement parallel with the axisof rotation of said work spindle, means for eifecting clamping action ofsaid chucking members on a work piece located on the axis of rotation ofsaid lathe in a direction substantially parallel to said axis so as torigidly hold said work piece against displacement radially of said axis,and

means independent of said chucking mechanism for axially positioning awork piece in said lathe lengthwise of said axis of rotation.

16. In a lathe, a rotatable work spindle, chuck ing mechanism onsaidwork spindle comprising work engaging members'adapted to move intoengagement with'a work piece on said Work spindle in a directionsubstantially parallel to the axis of rotation of said work spindle,means permitting axial floating movement in said chucking members, meanspreventing all movement of said chucking members in a planeperpendicular to said axis of rotation, and means associated with saidclamping member for effecting binding of said clamping members on saidwork piece.

' WILLARD L. GROENE.

